Water-heating coil



June 24, 1930.

- WATER HEATING COIL T. J, JOHNSTON Filed Oct. 20, 1927 paga.

'Ill

'Noms J. oHNs'rLSN- ATTORNEY.

Patented Jene 24, 193e f E lo save ofthe water through the ",T'A't'fE THOMASJ. 4if()J-IBTSL, OF BRADFORD; :PENNSYLVANIA.,y

wn''.rnitf:sunnitel corr. f

' Applieatiqn slee october eo, 1927. "serialvnef227,531. Y

T liis invention relatesk to an improvement onrcommonly used household water heaters.

Such lwater heaters 'aref generally providedv with water coils disposed in aver'tical casingV which holdsat the bottom thereof a gas heater for heating the coils and the water which passes therethrough.. -The cold; water generally enters into the coil atthe lower extremity thereof and passes upwards'. DuringV the pasbyr3 the gas flame.

In Y they use kor f such waterk heaters7 serious trouble has arisen due'. to `the tactv that the'v lowest convolution ofthe water coil'frequently'becomes punctured. i TvVhen a puncturel oc-'v curs in the-coil, it .cannot be'repairedvery eit'ectively except by the removal'ot the entire y coil and substitutinga new one therefor. Ef-

forts'are vfrequently'made to braze or solder the puncture and sometimeslthe punctured convolutionnis cut olif4 frointhe remainder of the coil andthe new convolutionis substituted in its pla-ce. Ineachotthese methods of repairing the burned out coil,rnew points ot weakness are substituted vfor lthe old. The soldered orbrazed puncture-is itself-weak and rarely lasts for a longperiod while the point or junction between the new eonvolutionandthe old ycoil alsoconstitutes `a weak pointwhere new punctures frequently 'appean f The ypuncturing described above isdue in part to each of two causes, yone cause being the local overheating'due to the constant playv of.- portions of the flame on one or more spots ofthe lowest convolution'. This may causey excessive overheating'at one 'spot ot the coil and followed'fby the destruction of the coil at thatvv particular spot-.1l The `other causeV is thefact that portions ofthe ycoil may happen to be constantly played upon by the oxidizing l portion ot the flame. This causes slow onildation of; thevinetal disposed at that particularspotl with the result that the material weakens atthatV point and ultimately causes a puncture. f l

Itis therefore the object otthe present invention toprotect the lowestconvolution of' the coil against any local overheating and against any :oxidation of thefmetal tube.

' It is the object of the present inventionY to coil7 lit is hea-ted' -which willclose'iy adhere' to the copper?tlib-y i of Figureh showing the coating in section.

subject the lowest-convolution of av heating coil to such treatment and fro/provide it with' a coating, lpreferably otretractory material., Y

which willprotect the lowest convolution, of the coil against local overheating and prevent Another object of theinventionis to pro-1 vide apcoating over the lowest convolutionof the' occurrence of punctures described above. l

the -coil which will serve to "distribute the Y. .A

heat evenlyl overthe surface ofthe convolu-jy tion, kthereby preventing any local overheat# .ingand preventing any punctures.

l Another object of the invention islto'pr'o.-

yvidethe lowest convolution ofthe coil` withy ya 'coating offmaterial which will not itself: j

be attacked bythe excessive heatV to which Y the lowest convolution is subjected, thereby e protecting the 'coil and which vwill at the Y saine timel notinterfere with the transmis# sion of heat from the burner to thel coilV and the water inthe coil. Y Y l Another vobject/ot the inventionis to vide a coatuig 'for the lowestconvolution ingandV will notk be subject tof accidental rei m'ovalinrom the copper tubing.` i

Other objects ofthe invention will be v.

derst'o'ocl from the description and the draw-f ings which constituteapart-ot this 4application. Y' l i f In the drawings:-

Figur'eflshows a heatingwcoilhaving its.

Alowest convolution provided with the coating.r

elfv

Figure'Q ris avi'ew taken along the line u Figures' fandel are ypartial' sections of the: f coil and ltheA mold: utilized the, application'I i 01' the Coating to the COi'l. f

Inv the "drawings, y,reference characterlO ...j

showsv the 'heating' coil which is v'provided with 'the cold waterV inletllA at its lowerextreinit-y-and hot' water outlet 12atitsfupper:r

end. fThe; coating of' refractory `'material' 13 isV shown applied `to aboutthree-quarters of the lowest convolution and 'extends romi a point near the cold water inlet to a point reaching about-three-quarters of they way around the convolution. The ends'of thev coating are tapered as shown at 14;.

" The coating 13 may, kif desired, befmade i i its original form while tliewater glass serves ofv any materia s which V'Wiii withstand ,the highrheat to which it is subjected and which will7 at 'the same time, adher e to the tubing and has the'quality of offering `the desired protection for'the tubing andis still capable of being applied in thin enough coatings so that it will not interfeie with .the transmission `of heat from the burner to the-water passing through the tube.

clay and ground asbestos orr'mineral wool mixed `with water glass as a binder, gives a coating which may be applied in thicknesses not exceeding one-quarter of an inch and Y brush or in any other manner. Y. theny subjected to baking in an oven or if er whichis already installed, it

pwhich will give all the desirable results enumerated above'. The proportions of the three ingredients of the coating may be varied considerably. The asbestos vor mineral wool due to its `fibrous structure7 serves toibindjthe fire clay and hold the same in as a binder to giveV the mixture theV desired consistency andcontinuit Y In the application of the above coating to theheating coil7 the lower convolution of the heating coil is first covered with a coating of water glass which may be applied with a. The coil is this entire process is appliedto ajwater heatis subjected A to baking merely by subjecting it to the (l. and. the subsequently applied Y feter of the mold 15 Yexceeds the outer diamburner which is a part of the water heater. This bakes and hardens the thin coating of water glass with the result that it offers a footing or a vbinding action between the coil consists of fire clayl'asbestos and water glass. The coating itself is preferably applied by meansof a split mold l5. The interior diameter of the coilfl() by anamountsufcient to provide the necessary thickness of coating.

The mixturelof.therefractory lmaterial isthe mold slightly in applied to each half of excess of the amount necessary.;- The -mold the mold are taperedas shown'at '17 After Vis then-applied to the "lowest convolution and the excessive material is removed and the two halves ofthe mold by means of the bolts 16. V,Thefreeends of .the ,mold and the refractory material is applied and clamped on theheating coil, itis n Y subjected toa baking Yprocess which need notA This lserves to harden Vthe refractory: material and'tolcause the same to adhere totheexceed a period of'fifteen or twenty minutes.

coating of `water glass on the coil. `After y the baking Vhas been completed and vafter thel apparatushas cooled,the moldiis removed,V l leaving' the desired coating on the coil.

Y j Ifliave found that a coil bearinga coating which haslbeen applied inthe manner describedv above, can withstand continuous application of heatV either from a gas burner or I have found that` a mixture of ground fireV Vthe like. t v Y Having described my invention', Iv do not wish to belimited by the specific embodiment shown herein since obviously many changes may be made by those skilled in coating which are clamped together coal fire for very long fperiodswithout being piinctured. in the mannerdescribed above and comparisioiicof suoli tests with untreated coils show that the coating described above d oes not interfere with the transmission of heatcfrom Repeated tests of coils treated the fiame or burner to the water in the coil; Y

l/Vhile the coating described 'above aords all the advantages sought by the present in- Y l vention7 the composition of the refractory layer may be varied by the admixture of a small Vamount of steel wool throughout the body ofthe refractory material. Thes'teel l Y upon the mixture and aids it in retaining its f When steel form; In the place of steel wool any other heat condi'icting material may be dispersed through the refractory composition when itl is in its pasty form, such as steel filings and the art without `departing from the spirit of my invention. l f VVhatI claim is: L

metallic vertically disposed heatingk coil adapted to cooperate with agas fiame to heat a stream of water passing through said coil and having its lowest Vconvolution exposed to the oxidizing action of the flame and to vdirect Y play of the flame, said lower convolution having a thin exposed heat conductingcoatj 1. A household water heater comprisingay `l ing for protecting said convolution against Y puncture, said coating comprising a bakedV layer ofnonmetallic refractory material.

' 2. A household water heater comprising a metallic vertically disposed `heating. coil adapted to cooperate with a'gas flame to heat a stream of water passing through said coil and having its lowest convolution exposed to the oxidizing action of theflame and to direct play of the flame, said lower convolution hav' ing a thin exposed heat conducting coating for protecting said'convolution against punc- Y 3. A household water heaterc'omprising a metallic vertically disposed Y heating coil adapted to cooperate with a gas fiame-to heat 4 a stream of water passing throughfsaid coilv and having its lowest convolution exposed kto the oxidizing action of the flame and to direct play of the fiame, said lower convolution hav- V.ing a tliin'exposed heat conducting coating for'protecting said vconvolution against puncture, said coating consisting of a baked layer `i of nonmetallic refractory materialV and'metal interspersed therein. Y

ture, said coating comprising a baked layer of non-metallic refractory material, and a layer of Water glass disposed between said Coating and said convolution.

In testimony whereof I aix myhand this 18th day of October, 1927.

THOMAS J. JOHNSTON. 

